#include <iostream>
#include <cstdio>

using namespace std;

int f(int n, int k) {
	int ret = 50 * n + int(50.0 * n / (0.8 + 0.2 * k));
	return ret;
}

int main() {
	int a, b;

	cin >> a >>  b;
	cout << f(a, b) << endl;
	return 0;
}